The present invention relates to an engine mounting for an engine accessory and, more particularly, to an engine accessory mounting which simplifies accessory installation and maintenance, reduces engine installation overall width and reduces wear and tear to the accessory when adjusting a drive belt tension effect thereon and which as well, minimizes possibility of damaging engine structure to which the mounting is made.
Automobiles and like vehicles operate from the rotary power output of an engine. Certain accessories, e.g., an alternator, utilize a part of engine rotary output by converting it into electric power which in turn is distributed to vehicle ignition and other vehicle electric power demands such as lighting, radio, electric operated windows etc. The alternator commonly is driven with an engine pulley operated drive belt, the alternator being attached or mounted to the engine cylinder block with a lower mounting bracket. Generally, an upper bracket also will be provided to connect the alternator with the engine such as to allow pivoting of the alternator about its lower bracket toward and away from the engine pulley to vary drive belt tension to a desired value.
In a known automobile engine, a cam shaft which operates the engine valves is linked to the crank shaft by a timing belt. Further and as shown in FIG. 6, a water pump 2 is provided on cylinder block 1. An accessory, alternator 3 by way of example, is located at a side of the engine. Pulleys 4 are attached to the rotary axes of each, and the pulleys are all linked by a driving belt 5.
Referring to FIG. 6, accessory 3 is supported by respective lower and upper brackets 7, 6. An elongated slotted hole 6a is formed in upper bracket 6 which extends from cylinder block 1. Accessory 3 is securely tightened to upper bracket 6 by a fastener (not shown) which passes through hole 8a in an upper flange 8 on accessory 3, the upper bracket 6 being fixed to the cylinder block 1, by a bolt 9b passing through a water pump housing extension and into an opening 6b at an end of the upper bracket.
Lower bracket 7 which is attached to cylinder block 1 has holes 7a in spaced flanges of the bracket so the accessory can be mounted to it with a bolt 9c passing through such flanges and a pair of flanges on the accessory such as is evident from FIG. 9. As a result, accessory 3 can freely move in a circular motion with bolt 9c as a pivoting center so that a position of accessory 3 relative to the engine can be adjusted. The adjustment of the tension in driving belt 5 is effected setting the tightened position of accessory 3 closer or farther from cylinder block 1. Published Japanese utility model number 60-187337 discloses that the tightening bolt can be moved using a tool to press on the flange of the accessory using the bracket as the support point.
Referring to FIGS. 7-9, it is seen that bearing case 10 of water pump 2 is attached to cylinder block 1 by a plurality of bolts (not shown). A hole 10a in a pump housing extension is used in the attachment of the upper bracket 6 to the engine this being in the housing extension as mentioned above.
Upper bracket 6 is an arc-shaped plate made, e.g., of aluminum alloy or cast iron. Slot 6a is formed along the arc. A stiffening flange 6c is formed on the upper edge of bracket 6 to strengthen it. The upper flange 8 of accessory 3 is anchored by tightening bolt 9a in slot 6a. The slot 6a it is noted is concentric with the pivot axis defined by bolt 9c with which the accessory is attached to lower bracket 7.
With this layout, upper flange surface 8 of accessory 3 and attachment surface la on the front side of cylinder block 1 do not become one surface. In the case where the difference in surface height is not equal that of upper bracket 6, an attachment surface 10b (which projects from the rim of cylinder block) is formed on bearing case 10 of water pump 2. Bearing case 10 serves as a spacer as well.
Referring to FIG. 12, when bearing case 10 is not used, attachment surface 1a projects from cylinder block 1. Upper bracket 6 on accessory 3 is formed as a curved surface with surface height differences and is attached to cylinder block 1.
When accessory 3 is attached to the engine, the upper bracket 6 is secured to the upper part of accessory 3. Depending on the tension in driving belt 5, there is a force pushing accessory 3 in the direction of the arrow A in FIG. 6. The force tries to push down accessory 3 and upper bracket 6 towards the front of the engine body.
Referring again to FIGS. 7-9, because upper bracket 6 is securely tightened to bearing case 10 of water pump 2, the tension in the belt has an effect on bearing case 10. There is a danger of a lowering of the surface pressure at the contact surface of bearing case 10 with part of the water pump 2 housing. In this case, influenced by leaning of accessory 3 and upper bracket 6, misalignment of driving belt 5 can increase and water leaks at the pump created.
As can be noted with reference to FIGS. 10-12, upper bracket 6 can be bent along the direction of arrow A in FIG. 6 and weakened greatly. By using a stronger material for the upper bracket, its deformation and the movement of accessory 3 can be prevented. But such would increase parts costs. Also, when belt misalignment increases, belt vibrations and noise become worse and this is undesirable.
From FIG. 7 it is noted that upper bracket 6 projects from accessory 3 by an adjustment length a, and the width of the engine becomes larger. This has a disadvantage as the position adjustment of accessory 3 goes against the tension, and the tightening of bolts is a complex procedure. During the procedure, since the accessory is supported by available tools, care must be taken not to damage the surrounding parts in case the tool slips.
Another shortcoming of prior accessory mountings for mounting the accessory to the automobile engine is the unnecessary complex construction, cost and utilization of the lower mounting bracket with which the accessory is pivoted mounted to the cylinder block or other suitable engine structure, such mounting requirement already having been mentioned above but more elaborate discussion of that shortcoming now being made.
With reference to FIGS. 19 and 20 which detail another prior engine accessory mounting, upper bracket 102 and lower bracket 103 are mounted to the side of engine 101. Lower bracket 103 provides an axis about which accessory 104 can move in a circular motion along the slotted hole 102a of upper bracket 102, upper bracket 102 being arc shaped. Upper bracket 102 is tightened to engine 101 with a bolt passing through opening 102b at an end of the bracket. On lower bracket 103, bolts 107, 109 pass through lower flanges 106, 108 of accessory 104 so that accessory 104 can move freely in a circular pivoting motion relative to the engine. Bolt 111 passes through an upper flange 110 of accessory 104 and slotted hole 102a. By changing the position where bolt 111 is tightened, accessory 104 can be moved, and the tension in the accessory driving belt adjusted, the driving belt receiving drive from pulley 112 on the engine.
Referring to FIG. 21, accessory 104 carries upper flange 110 and a pair of lower flanges 106, 108. A female screw hole 110a is formed on upper flange 110, and a bolt attachment holes 113 are formed on the lower flanges 106, 108 of the accessory.
Lower bracket 103 commonly is made of cast aluminum alloy or cast iron. A pair of upright flanges 103b, 103b are formed on a lower bracket web part 103a. Web part 103a contacts against engine 101. An end edge of web part 103a is bent to form an in turned part 103c which abuts against a front part of engine 101. Strengthening ribs 103d are formed on web part 103a orthogonal to flanges 103b, 103b. Attachment holes 113 are formed on web part 103a and in turned part 103c.
Female screw threads 103e are formed in the pair of upright parts 103b, 103b. Accessory 104 is attached to lower bracket 103 with the pair of lower flanges 106, 108 sandwiched between the flanges 103b, 103b of the lower bracket, the bolts 107, 109 passing through the flanges 106, 108 and into flanges 103b. In another case, the accessory 104 can be securely tightened to a case of a cam driving device. The accessory pulley can be supported by an L-shaped bracket which tightens from the side and front along the case and cylinder head (refer to Japanese utility model number 64-15728).
Where lower bracket 103 is cast from a light alloy, the size must be made bigger at times to provide proper strength. Further, production requirements may mandate areas needing thickness increase. As a result, the size and weight of the bracket becomes unnecessarily large. Another disadvantage is the number of bolts needed for attachment to engine 101. Accessory 104 and lower bracket 103 are secured the screws entering female threads 103e, 103e on lower bracket 103 and with two bolts 107, 109. If the configuration is made so that it is tightened together by passing through a single bolt, ribs 103d must be added as reinforcement and lower bracket 103 becomes larger.
When size and weight become large, the vibrations of accessory 104 and engine 101 become compounded, and much rigidity is required in order to withstand the vibrations. In addition, secure tightening is needed from the other side by bolts 114. But, to tighten lower bracket 103 with bolts 114 from the other direction complicates the assembly process. Attaching accessory 104 to lower bracket 103 by tightening two bolts 107, 109 from two direction also lowers the productivity of the assembly procedure.
In addition to complicating mounting of the accessory as when making a replacement, the many parts used in the mounting add to the cost of the mounting.
It is desirable therefore, that there be provided an engine mounting for an automobile engine accessory with upper and lower brackets which simplifies installation and replacement of the accessory as well as the tension adjustment of any drive belt with which the accessory is driven from the engine.